Reproducible Abnormalities and Diagnostic Generalizability of White Matter in Alzheimer's Disease / 神经科学通报·英文版

Alzheimer's disease (AD) is associated with the impairment of white matter (WM) tracts. The current study aimed to verify the utility of WM as the neuroimaging marker of AD with multisite diffusion tensor imaging datasets [321 patients with AD, 265 patients with mild cognitive impairment (MCI), 279 normal controls (NC)], a unified pipeline, and independent site cross-validation. Automated fiber quantification was used to extract diffusion profiles along tracts. Random-effects meta-analyses showed a reproducible degeneration pattern in which fractional anisotropy significantly decreased in the AD and MCI groups compared with NC. Machine learning models using tract-based features showed good generalizability among independent site cross-validation. The diffusion metrics of the altered regions and the AD probability predicted by the models were highly correlated with cognitive ability in the AD and MCI groups. We highlighted the reproducibility and generalizability of the degeneration pattern of WM tracts in AD.

Comparative study of white matter diffusion properties in vulnerable and resistant individuals to continuous attention after short term sleep deprivation / 中华行为医学与脑科学杂志

Objective:To investigate the differences of white matter diffusion properties between vulnerable and resistant individuals to continuous attention after sleep deprivation.Methods:According to the psychomotor vigilance test performance before and after sleep deprivation, the participants were divided into the vulnerable group( n=24) and resistant group( n=25). All participants underwent diffusion tensor imaging (DTI) scans.Tract based spatial statistics(TBSS) was used to compare fractional anisotropy(FA), mean diffusivity(MD), axial diffusivity(AD), radial diffusivity(RD) maps between the two groups.Spearman correlation analysis was conducted by SPSS 24.0 to investigate the relationships between the altered DTI metrics and PVT task performance. Results:(1) Compared with resistant group, FA value of vulnerable group decreased in the body of corpus callosum(x, y, z=-8, 9, 25, t=-7.855), right superior longitudinal fasciculus(x, y, z=-39, -7, 26, t=-6.252), bilateral anterior limb of internal capsule(x, y, z=-13, 8, 13, t=-5.235; x, y, z=12, 8, 3, t=-5.024) and right posterior thalamic radiation(x, y, z=-26, -56, 17, t=-5.469)(TFCE corrected, P<0.05, cluster size≥50 voxel). (2) Compared with resistant group, MD value of vulnerable group increased in the body of corpus callosum(x, y, z=-3, -6, 26, t=7.613), right superior longitudinal fasciculus(x, y, z=-31, -19, 38, t=5.314), bilateral anterior limb of internal capsule(x, y, z=-16, 7, 8, t=6.898; x, y, z=15, 5, 7, t=6.652), splenium of corpus callosum(x, y, z=27, -53, 17, t=6.541), and AD value increased in the right superior longitudinal fasciculus(x, y, z=-33, -19, 39, t=4.892), splenium of corpus callosum(x, y, z=-22, -49, 21, t=5.450), genu of corpus callosum(x, y, z=4, 26, 0, t=4.332), as well as RD value increased in the right superior corona radiata(x, y, z=-17, 1, 33, t=7.558), body of corpus callosum(x, y, z=4, -8, 26, t=6.699), right anterior limb of internal capsule(x, y, z=-12, 7, 3, t=5.212) (TFCE corrected, P<0.05, cluster size≥50 voxel). (3) Correlational analysis revealed that the negative correlations were found between PVT task performance and the FA value in the right superior longitudinal fasciculus( r=-0.492, P<0.001), right anterior limb of internal capsule( r=-0.510, P<0.001), right posterior thalamic radiation( r=-0.502, P<0.001) and body of corpus callosum( r=-0.464, P<0.001). The positive correlations were found between PVT task performance and the MD value in the body of corpus callosum( r=0.500, P<0.001), right superior longitudinal fasciculus( r=0.499, P<0.001), splenium of corpus callosum( r=0.462, P<0.001), right anterior limb of internal capsule( r=0.471, P<0.001), and AD value in right superior longitudinal fasciculus( r=0.643, P<0.001), as well as RD value in right superior corona radiate( r=0.498, P<0.001) (Bonferroni corrected, P<0.003). Conclusion:Differences in the microstructural characteristics of white matter fiber tracts in specific brain regions may constitute the potential neuropathological basis for the phenotypes of vulnerable and resistant individuals to continuous attention after sleep deprivation.

Advance in Role of White Matter Tracts in Aphasia: Based on Dual Stream Language Model (review) / 中国康复理论与实践

Previous researches about the brain mechanism of aphasia mainly focused on the correspondence between cortical brain regions and language function. Now, more and more researches have found that the connection of white matter tracts in the brain plays an important role in language function. Dual-stream language model hypothesizes that the process of language can be considered as two parallel pathways, dorsal and ventral. The white matter fibers of dorsal stream include arcuate fasciculus and superior longitudinal fasciculi, which are mainly involved in the production of language. The white matter fibers of ventral stream include the inferior frontal-occipital fasciculus, inferior longitudinal fasciculus and uncinate fasciculus, which are mainly responsible for language understanding. The conception of connection mode and specific functional role of these fibers in the language network of patients with aphasia is helpful for the assessment of the features and severity of the patient's language dysfunction and outcome, to guide clinical precision rehabilitation. More researches are needed to elaborate the interaction between the dorsal and ventral streams to well know the brain's language network processing mechanism.